TANK CLEANING SYSTEM

Abstract: A tank cleaning system comprising a turbine and a gear box situated in a housing with an inlet and an outlet, wherein bypass means are provided between the turbine and the inlet. Said bypass means make it possible to lead part of the cleaning fluid past the turbine in order to adjust the speed of rotation of the turbine irrespective of the flow of cleaning fluid.

Description: TANK CLEANING SYSTEM The present invention relates to a tank cleaning system, primarily for washing the cargo tanks of tankers and comprising a driving system that consists of a turbine, which is positioned in a turbine pipe, and a gear box, which has an ingoing shaft driven by the turbine and an outgoing shaft driving a washer head, said tank cleaning system also comprising a housing which is provided with an inlet connected to a source of supply of cleaning fluid and an outlet for supplying the cleaning fluid or conveying the cleaning fluid to the washer head, said turbine being placed inside the housing, between which turbine and said source of supply there are provided bypass means designed to lead to the turbine pipe a major or minor share of the cleaning fluid supplied through the inlet, and the shares of the cleaning fluid are brought together in the housing and then conveyed to the washer head through the outlet of the housing. NO publication No. 145,608 describes such an apparatus in which the turbine is provided with means for adjusting the speed of rotation. These means make it possible to adjust the angle of the turbine blades and thus the speed of rotation of the turbine at a given flow of cleaning fluid. Furthermore, the apparatus is provided with a gear box situated under the pipes and channels through which the cleaning fluid passes. The disadvantage of this apparatus is that the means for adjusting the speed of rotation of the turbine are very complicated and also consist of many small individual parts. As, among other things, the apparatus is intended for being secured to the decks of tankers where physical strain and the surrounding environment are sometimes very rough, there is a great risk that the many individual parts will be damaged and consequently give rise to subsequent operation stoppages. Other prior art apparatuses, e.g. those described in GB patent application No. 2,096,455; in GB patent application No. 2,231,487; and in SE publication No. 445,823, are also provided with a gear box but not with means for adjusting the speed of rotation. However, the gear boxes are all positioned outside the track of the cleaning fluid through the apparatus. The disadvantage of this position is that the construction of the apparatus is made complicated by the necessity to provide transmission between the turbine situated in the track of the cleaning fluid to the gear box situated outside the track of the cleaning fluid and on to the washer head transmission shaft which, like the turbine, is situated in the track of the cleaning fluid. It is the object of the present invention to remedy the disadvantages which prevail in connection with the apparatuses of the prior art and thus disclose a tank cleaning system in which it is possible in a simple manner to adjust the speed of rotation of the turbine irrespective of the flow of cleaning fluid. This object is achieved by a tank cleaning apparatus which is characterized in that the bypass means are provided in the turbine pipe and consist of openings in the turbine pipe between the inlet and the turbine and of a jacket which is designed to be displaced in relation to the turbine pipe and to cover part of the openings in a variable manner. In an apparatus with the above-mentioned characteristics one obtains a very simple and easy, and consequently operationally reliable, manner of varying the speed of rotation of the washer head irrespective of the flow of cleaning fluid. This offers the advantage that it is made possible to adjust the flow of cleaning fluid and the speed of rotation of the washer head independently and under consideration of the product of which the tank is to be cleaned. In tanks which are to be cleaned of heavy products, it will be advantageous to have a high flow of cleaning fluid but a low speed of rotation of the washer head. In this manner each surface unit of the tank will be swept for a relatively long period with a high pressure of cleaning fluid. In tanks which are to be cleaned of light products, on the other hand, it will be advantageous to maintain the high flow but to have a high speed of rotation of the washer head so that the time used for cleaning the tank is minimized. At their outer end the turbine blades of a preferred embodiment are secured to a reaction ring which delimits the outer circumference of the turbine wheel and causes fringe effects in connection with the operation of the turbine to be avoided. Thus it has turned out that the effectiveness of a turbine is up to 30% higher in a turbine with a reaction ring compared to a turbine without that ring. The turbine and the gear box will preferably be assembled in one and the same housing in which the cleaning fluid is led into one end of the housing and out of the other end. This requires that the gear box is sealed in order to avoid that cleaning fluid penetrates into it. Accordingly, the gaskets of the gear box are preferably made from polyethylene, high-molecular (PEHD, PEWST tm , PEHWO ,m ). In order to prevent any lubricant from the gear box from penetrating into the cleaning fluid even though the gear box is sealed, the individual bearings of the gearwheels and the shafts are produced from materials which make it possible to let the gear box operate dryly, i.e. a gear box in which it is not necessary to use lubricants. PTFE (or teβon ® ), which has a very low friction coefficient and is very heat resistant, is preferably used for the bearings. Of course this makes heavy requirements on the construction and dimensioning of the individual parts of the gear box, but this is counterbalanced by the advantages obtained by not risking that cleaning fluid will penetrate into the gear box and/or that any oil leak from the gear box will occur. However, it will still be possible alternatively to use traditional wet operation gear boxes, i.e. requiring lubrication. The washer head, which is placed at the end of a pipe extending in prolongation of the outlet of said housing, consists of a cabinet with an ingoing shaft which is an extension of the outgoing shaft of the gear box and extends through said pipe and an outgoing shaft where the actual nozzles of the washer head are mounted. The nozzles typically consist of one to four nozzles mounted perpendicularly on the outgoing shaft, the longitudinal axis of the nozzles crossing the longitudinal axis of the outgoing shaft. Alternatively, the longitudinal axis of the nozzles may be out of level with the shaft so that an increased "throwing effect" is obtained during the rotation of the washer head. The transfer of the rotation of the ingoing shaft to the rotation of the outgoing shaft is effected via a differential gear having a crown wheel and a drive pinion. The differential gear is further constructed in such a manner as to obtain a rotation of the cabinet itself in relation to the pipe extending in prolongation of the outlet. It is noted that the washer head is not part of the invention but the reference thereto is included for the sake of completeness. A preferred embodiment of the bypass function according to the invention is provided at a slidable jacket placed around the turbine pipe and intended for being slid in order to cover more or less of the openings in the turbine pipe. Said openings constitute the actual bypass for the cleaning fluid as the fluid which is led through these openings is not led through the turbine. Thus, by covering up the openings completely, all of the cleaning fluid will be led through the turbine, which consequently obtains a high speed of rotation, whereas the speed of rotation of the turbine is at its minimum when only a very small part of the cleaning fluid is led through the turbine, which will be the case when the openings are completely uncovered. In addition, any intermediate position will be possible so that the speed of rotation of the turbine may be varied infinitely or stepwise. In a preferred embodiment the openings are designed in such a manner as to obtain linearity between the axial angle of the cabinet in relation to the turbine pipe and the speed of rotation of the turbine. In an alternative embodiment the turbine is provided with means of braking which will stop the turbine when the openings are completely uncovered so that the turbine and, consequently, the washer heads are prevented from rotating. DESCRIPTION OF THE DRAWING The invention will now be described in further detail with reference to the attached drawing, in which fig. 1 illustrates the principle of an embodiment of the invention, and fig. 2 is a cross section of a second specific embodiment of a tank cleaning system according to the invention, and fig. 3 is a cross section of an alternative specific embodiment of a tank cleaning system according to the invention. Fig. 1 shows the general principle of a tank cleaning system according to the invention. Cleaning fluid which is pumped out of a tank, e.g. by the cargo pumps of a tanker, is led in at the connection flange to the bypass valve 2. The specific construction of the bypass valve 2 is not determined in detail. The requirement on the valve is that it makes it possible to lead one part of the cleaning fluid to a turbine 3 and another past the turbine. The turbine 3 drives a shaft 4 via a gear box 5. The shaft 4 extends through a fixed pipe 6 to a washer head 7. The washer head 7 consists of a cabinet 8, wherein the rotation of the shaft 4 is transmitted to provide both a rotation of the cabinet 8 about a vertical axis V and a rotation of a nozzle means 9 around a horizontal axis H. The part of the cleaning fluid which is led through the turbine 3 is led out, after having passed the turbine, through openings 10 and mixed with the part which was led past the turbine 3. Then the cleaning fluid is led on through the pipe 6 to the washer head 7 and out through nozzles 11 on the nozzle means 9. The washer head 7 and its rotation around the vertical axis V, and the nozzle means 9 and its rotation around the horizontal axis H are known within the prior art and thus will not be described in detail. Fig. 2 shows an alternative and more detailed embodiment of a tank cleaning system according to the invention. A housing 20 is provided with an inlet 21 and an outlet 22, which are situated in a top and a bottom cover 23, 24, respectively. Between the inlet 21 and the outlet 22 a turbine pipe 25 and a turbine 26 are provided in a turbine housing 27, which is in direct contact with a gear box 28 with an outgoing shaft 29. Around the turbine pipe 25 a jacket 30 is mounted which is slidable axially in relation to the pipe 25. Said jacket 30 is in mesh with a traction wheel 31 mounted on and secured to a shaft 32 by means of a key 33 which shaft is intended to be connected to a motor (not shown). The inlet of the tank cleaning system is constituted by a flange 34 which is secured to the top cover 23 of the housing by means of bolts 35 and which is provided with seals 36 in order to prevent the cleaning fluid from running out between the flange 34 and the top cover 23. It is possible to replace the flange 34 in order to provide the possibility of connecting the system to different types of pumping devices for the cleaning fluid. The top cover 23 is mounted to the sidewalls 37 of the housing 20 by means of other bolts 38. This makes it possible to remove it for any servicing of the parts inside the housing 20. Between the top cover 23 and the sidewalls 37 there are also seals 39. The inlet 21 passes into a mouth 40 on the turbine pipe 25. The turbine pipe 25 is provided with openings 41 which are rectangular in the embodiment shown. It will be possible, however, to design the openings with any geometrical shape, preferably a shape which ensures linearity between the slide of the jacket 30 and the speed of rotation of the turbine 26. At the end of the turbine pipe 25 the turbine 26 is situated. It consists of a set of firmly mounted guide blades 42 which are secured to a hub 43. The actual turbine rotor is mounted under said guide blades. The turbine rotor comprises a hub 44, which is shrunk or otherwise secured to a turbine shaft 45. Turbine blades 46 are secured to the hub at one of their ends and to a reaction ring 47 at their other end. Thus, the reaction ring 47 delimits the outer circumference of the actual turbine rotor. Between the turbine 26 and the gear box 28, the turbine pipe 25 is provided with openings 48 for outlet of the part of the cleaning fluid that is led through the turbine 26. The turbine shaft 46 forms the ingoing shaft for the gear box 28. The gear box 28 is constituted by a separate gear housing inside the housing 20 and comprises sidewalls 49 and a top cover 50, the bottom cover of the gear box 28 being constituted by the bottom cover 24 of the housing 20. The transition between the turbine pipe 25 and the top cover 50 of the gear box 28 is provided with seals 51 of high-molecular polyethylene and washers 52 in order to prevent cleaning fluid from penetrating into the gear box. The top cover 50 of the gear box 28 is held in contact with the sidewalls 49 of the gear box by means of through-going bolts (not shown), which extend from the bottom 24 of the gear box. Between the top cover 50 and the sidewalls 49 there is further provided a seal 53 of high-density polyethylene. The gear box 28 is provided with an ingoing shaft constituted by the turbine shaft 46. a main shaft 54 connected to the outgoing shaft 29, and an intermediate shaft 55. The ingoing shaft 46 is embedded in the top cover 50 of the gear box 28 via a single-row angular contact ball bearing 56. In one end 57 the main shaft 54 is embedded in the ingoing shaft 46 via a slide bearing 58 and in the other end 59 in the bottom cover 24 via a single-row angular contact ball bearing 60. The intermediate shaft 55 is embedded in the top cover 50 and bottom cover 24 of the gear box 28 and are fixed by means of a pin 61 so that the intermediate shaft 55 is unable to rotate. In the end extending into the gearbox, the ingoing shaft 46 is provided with a toothing 62. The intermediate shaft 55 is provided with a first and a second gearwheel 63, 64 which are both attached to the shaft 55 via slide bearings 65. The main shaft 54 is provided with a third and a fourth gearwheel 66, 67, the third gearwheel 66 of which is attached to the shaft 54 via slide bearings 68 and the fourth gear wheel 67 is secured to the shaft 54 by means of a key 69. In a preferred embodiment like the one illustrated in the figure, the slide bearings 65, 68 between the shafts 54, 55 and the gearwheels 63, 64, 66, 67 and between the ingoing shaft 46 and the main shaft 54 are manufactured from PTFE (or teflon ® ). The advantage of using this material is, as mentioned earlier, primarily the possibility of letting the gears run dryly due to the low friction coefficient and the high resistance to thermal influences. In addition, the gearwheels 63, 64, 66, 67 are retained in their axial direction by means of axial or thrust bearings 70. Where the main shaft 54 extends through the bottom cover 24, the gear box 28 is provided with a seal box 71 in order to prevent here as well that cleaning fluid will penetrate into the gear box. The outgoing shaft 29 extends further through the outlet 22 and down to the washer head (not shown). The outlet 22 leads into a socket 72 which is intended to be connected to one end of a firm pipe (not shown) in the other end of which the washer head is mounted. The socket 72 is secured to a bottom flange 73 which is bolted to the bottom cover 24 of the housing 20 by means of bolts 74. Like the top flange 23, the bottom flange 73 is replaceable so that different types of washer heads may be used in connection with the system according to the invention. The flange 73 is designed in such a manner that when it is mounted on the bottom cover 24 of the housing 20, a cofferdam 75 is formed between the outside 76 of the bottom cover 24 and the inside 77 of the flange 73. In said cofferdam 75, the cleaning fluid is received after having been led through a passage 78 in the bottom cover 24 of the housing 20 before the fluid is led on through the outlet 22 to the washer head. For adjusting the speed of rotation of the turbine 26, the jacket 30 is slid up around the openings 41 causing a larger or lesser part of the openings to be covered. The jacket 30 is provided on its outside with a thread 79 spiralling along the outside. A corresponding thread 80 is provided on the traction wheel 31, and the jacket 30 is slid by rotating the traction wheel 31 causing the jacket 30 to be slid up or down along the turbine pipe 25 depending the direction of rotation of the traction wheel. The traction wheel 31 is, as mentioned, mounted on a shaft 32 extending through a sleeve 81 which is secured to the top cover 23 of the house 20. By means of an inner spacer bushing 82, the shaft 32 is embedded in slide bearings 83 in the sleeve 81, and the sleeve is provided with seals 84 in order to prevent leakages of cleaning fluid. The outer end of the shaft 32 is intended to be connected to an adjustable motor (not shown) which is adjusted either continuously or stepwise. Figure 3 illustrates an alternative embodiment of the adjustment of the speed of rotation of the turbine 26. In the shown embodiment a jacket 30' is slid along the openings 41 of the turbine pipe 25 so that a larger or smaller part of the openings are covered. On its outside the jacket 30' is provided with a toothing 86 extending along the outside of the jacket. A corresponding toothing 86 is provided on the traction wheel 31 and the jacket 30' is slid by rotating the traction wheel 31 causing the jacket to be slid around the circumference of the turbine pipe 25 depending on the direction of rotation of the traction wheel. Besides the individual constructive differences between the embodiment illustrated in figure 3 and the one illustrated in figure 2, there is no difference in the way in which the jacket, and thus the speed of rotation of the turbine, is regulated. The individual parts of a tank cleaning system according to the invention, such as disclosed in the above description, may be designed and combined in many other ways than those illustrated. Due to the complexity of the construction, it will be possible to achieve the same purposes and advantages in other constructions as the advantages of the illustrated constructions. Therefore, the embodiments shown in the figures are only to be seen as possible embodiments of a system according to the invention but they are not to be seen as a limitation of the invention, the latter being defined and determined

Claims: in the claims. CLAIMS 1. A tank cleaning system, primarily for washing the cargo tanks of tankers and comprising a driving system that consists of a turbine, which is positioned in a turbine pipe, and a gear box, which has an ingoing shaft driven by the turbine and an outgoing shaft driving a washer head, said tank cleaning system also comprising a housing which is provided with an inlet connected to a source of supply pf cleaning fluid and an outlet for supplying the cleaning fluid or conveying the cleaning fluid to the washer head, said turbine being placed inside the housing, between which turbine and said source of supply there are provided bypass means designed to lead to the turbine pipe a major or minor share of the cleaning fluid supplied through the inlet, and the shares of the cleaning fluid are brought together in the housing and then conveyed to the washer head through the outlet of the housing, characterized in that the bypass means are provided in the turbine pipe and consist of openings in the turbine pipe between the inlet and the turbine and of a jacket which is designed to be slid in relation to the turbine pipe and to cover part of the openings in a variable manner. 2. A tank cleaning system according to claim 1, characterized in that also the gear box is placed inside the housing. 3. A tank cleaning system according to any of the preceding claims, characterized in that the jacket is provided with an outer toothing that is in mesh with a driving gearwheel which is designed to drive the jacket axially in relation to the turbine pipe and which is positioned on a shaft which is driven by an adjustable motor. 4. A tank cleaning system according to any of the preceding claims, characterized in that the jacket is provided with an outer toothing which is in mesh with a driving gearwheel which is intended to drive the cover axially along a circumference in relation to the turbine pipe and which is positioned on a shaft which is driven by an adjustable motor. 5. A tank cleaning system according to claim 1 or 2, characterized in that the bypass means comprise a bypass valve with an inlet opening connected to a source of supply and to at least two outlet openings one of which is connected to the turbine and the other one is connected to the housing, and that the bypass valve body is provided for adjustment of the flow of cleaning fluid to either of the outlet openings. 6. A tank cleaning system according to any of the , preceding claims, characterized in that the gear box is sealed against cleaning fluid penetration and that the gear wheels and shafts are produced from materials which allow the gear box to operate without the use of lubricants. 7. A tank cleaning system according to any of the preceding claims, characterized in that the openings in the turbine pipe are substantially pear- shaped, their pointed end turning towards the inlet and their blunt end turning towards the turbine. 8. A tank cleaning system according to any of the preceding claims, characterized in that the washer head is provided in extension of the outgoing shaft of the gear box and comprises a cabinet with an ingoing and an outgoing shaft which is directed substantially perpendicularly in relation to the ingoing shaft and whereupon a number of nozzles are mounted, the longitudinal axis (axes) of said nozzles being directed substantially in a right angle in relation to the outgoing shaft. 9. A tank cleaning system according to any of the preceding claims, characterized in that at the outer end of the turbine blades the turbine is provided with a reaction ring. 10. A tank cleaning system according to any of the preceding claims, characterized in that the slide bearings of the system are produced from PTFE.

Inventors: RASMUSSEN JAN BERG, RASMUSSEN, JAN, BERG
Applicants: RASMUSSEN JAN BERG, RASMUSSEN, JAN, BERG
Application year: 1994
Main classification: B05B3
IPC codes: B05B3, B08B9, B63B57